The gang that couldn’t shoot straight

SEATTLE – About that Cal-Stanford rubber match for the championship of the Pac-12 Conference women’s basketball tournament?

Never mind.

In a stunning reversal of its season-long run of excellence, Cal played its worst game of the season in losing to UCLA 70-58 in a semifinal game Saturday night at the KeyArena.

Ranked No. 5 nationally before the game, the 28-3 Bears will sit and stew about this unexpected result until their bid to the NCAA Tournament is announced on March 18. UCLA, 25-6, goes on to play for the tournament title on Sunday.

“In the locker room we were all kind of sad, but we have three losses the entire year,’’ Cal guard Layshia Clarendon said. “This doesn’t ruin our season at all. It’s a wakeup call. It’s how we respond to it.’’

Assessing her team’s NCAA Tournament positioning, Cal coach Lindsay Gottlieb said, “I think our body of work is pretty good. We could have helped ourselves in this tournament had we won it. The only option is to look forward to the next tournament. We’ll use this to help us.’’

Miserable shooting — epic-bad, really — doomed the Bears in the first half. They made only 5 of 25 shots overall and were skunked beyond the three-point arc: 0-for-11.

“I don’t think we ever think we’re going to miss that many shots,’’ Gottlieb said. “We didn’t see this coming.’’

There would be no comeback from a 35-14 halftime deficit for Cal even with a 44-35 edge in the second half. Overall, Cal shot 29.5 percent, meaning it missed 43 of the 61 shots it attempted.

“These are the shots we take in practice,’’ said point guard Brittany Boyd, who made 4 of her 11 attempts. “I don’t think they were bad shots. They just didn’t go in. I credit their defense. Their defense was the key.’’

UCLA came out in a 2-3 zone defense and stayed with it the entire game. It stymied Cal inside and enabled the Bruins to out-rebound one of the top rebounding teams in the country by 41-36. Post players Markel Walker (23 points), Jasmine Dixon (15 points, 12 rebounds and Alyssia Brewer (14 points) did the damage for UCLA.

In the decisive first half, Cal fell behind early and never mounted a serious threat to strike back, hamstrung by shooting that at times dipped below 20 percent. The UCLA lead reached 45-19 in the second half before the Bears finished out the game on a 39-25 run.

“They really packed it in in the paint,’’ Boyd said. “The zone killed our energy and our transition. By them making shots (the Bruins hit 30 of 61 from the floor), it was hard for us to get in transition, and that’s where we get most of our points in transition.’’

The Bears will now transition from the conference tournament to the one that really counts.

John Crumpacker is a San Francisco Chronicle staff writer. E-mail: jcrumpacker@sfchronicle.com Twitter: @crumpackeroncal